loadModel() options break without fileType and ignore flipU/flipV #9302

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• WebGPU
• p5.strands
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

2.3.2 / current main

Web browser and version

Chromium 151

Operating system

Fedora Linux

Steps to reproduce this

The documented loadModel(path, options) overload breaks depending on whether fileType is included.

async function setup() {
  createCanvas(100, 100, WEBGL);

  // Throws: fileType.toLowerCase is not a function
  await loadModel('model.obj', { flipU: true });

  // Loads, but flipU is ignored
  await loadModel('model.obj', {
    fileType: '.obj',
    flipU: true
  });
}

Options like { normalize: true } or {} also throw when fileType is omitted. With fileType present, flipU / flipV are ignored, although calling model.flipU() / model.flipV() afterwards works.

Expected: loadModel(path, options) should work without requiring fileType, and the flip options should be applied.

I traced it to the options parsing here:

fileType is reassigned before flipU / flipV are read, so without fileType the options object eventually reaches .toLowerCase(), while with it the flags are read from a string.